Color change perfume systems

Abstract

This invention provides a color change perfume system in which color is caused to change when the perfume in the system is effectively exhausted to the atmosphere. The invention also provides air fresheners and the like consisting of a porous carrier impregnated with the perfumed color change system.

What is claimed is: 
     
       1. A colour change perfume system comprising (1) a volatile acid or base, (2) a perfume adapted to pass into the atmosphere at a selected rate, and (3) a pH indicator, the volatile acid or base being selected and being present in such amount as to volatize at about the same rate as the perfume, thereby causing the pH indicator to change colour when the perfume is effectively exhausted. 
     
     
       2. A system as claimed in claim 1 in which component (1) is a volatile acid. 
     
     
       3. A system as claimed in claim 2 in which the volatile acid is acetic acid. 
     
     
       4. A system as claimed in claim 2 in which the volatile acid is hydrochloric acid. 
     
     
       5. A system as claimed in claim 1 in which component (1) is a volatile base. 
     
     
       6. A system as claimed in claim 5 in which the volatile base is an amine. 
     
     
       7. A system as claimed in claim 1 in which the system is clear and aqueous and comprises a surfactant and a solvent selected to enhance the solubility of the perfume in water. 
     
     
       8. A system as claimed in claim 7 in which the solvent is a mono- or polyhydric alcohol. 
     
     
       9. A system as claimed in claim 1 in which at least 50% by weight of the system consists of water and the system comprises an amount of an emulsifying agent sufficient to emulsify the perfume into the water phase of the system. 
     
     
       10. A colour change perfume system as claimed in claim 1 in combination with an impregnatable porous carrier. 
     
     
       11. A colour change perfume system comprising (1) an alkali which reacts with carbon dioxide absorbed from the air, (2) a perfume adapted to pass into the atmosphere at a selected rate, and (3) a pH indicator, the alkali being selected and being present in such amount as to react with carbon dioxide at about the same rate as the perfume passes into the atmosphere, thereby causing the pH indicator to change colour when the perfume is effectively exhausted. 
     
     
       12. A system as claimed in claim 11 in which the alkali is sodium hydroxide. 
     
     
       13. A system as claimed 11 in which the system is clear and aqueous and comprises a surfactant and a solvent selected to enhance the solubility of the perfume in water. 
     
     
       14. A system as claimed in claim 13 in which the solvent is a mono- or polyhydric alcohol. 
     
     
       15. A system as claimed in claim 11 in which at least 50% by weight of the system consists of water and the system comprises an amount of an emulsifying agent sufficient to emulsify the perfume into the water phase of the system. 
     
     
       16. A colour change perfume system as claimed in claim 11 in combination with an impregnatable porous carrier.